Temperature-Robust Polymer Shroud For Roller Bearing Seal

ABSTRACT

A temperature-robust polymer shroud for a roller bearing seal includes a shroud body and an inner diameter leg defining respective portions of a single continuous part. The shroud body encircles a rotation axis of the polymer shroud and extends predominantly in directions orthogonal to the rotation axis from an inner diameter to an outer diameter. The inner diameter leg connects to the shroud body at the inner diameter and encircles the rotation axis, wherein, along the entire inner diameter of the shroud body, the inner diameter leg is oriented at an oblique angle to the rotation axis to extend both (a) radially inward from the inner diameter and (b) axially away from the inner diameter along a first direction parallel to the rotation axis. A roller bearing seal includes a seal case, an elastomer lip, and the temperature-robust polymer shroud.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/791,186, filed Oct. 23, 2017, which is incorporated hereinby reference in its entirety.

BACKGROUND

Demand for lower freight transportation cost is driving up the averagefreight car weight around the world. To carry heavier weight, thefreight cars must be equipped with strong bearings capable of carryingboth axial and radial loads.

Tapered roller bearings efficiently carry both axial and radial loads. Atapered roller bearing includes one or more rows of tapered rollers.Each row encircles the rotation axis of the bearing. Each tapered rollerhas the shape of a truncated cone. This geometry allows the taperedroller bearing to support axial loads (loads parallel to the rotationaxis of the bearing). A popular choice for freight cars is thedouble-row tapered roller bearing which has two rows of tapered rollers.The two rows are tapered in opposite directions to locate the shaft, orjournal, in both directions along the rotation axis.

Tapered roller bearings, as well as other types of roller bearings,operate with a lubricant within the bearing to reduce friction betweenthe rollers and the raceways on which the rollers roll. To contain thelubricant within the bearing and to prevent water, dirt, and othercontaminants from entering the bearing, the bearing is sealed. The sealmay be a contact seal that forms a physical barrier between the insideof the bearing and the external environment. Common contact sealsinclude a rubber ring that seals a gap between a rotating andnon-rotating portion of the roller bearing.

SUMMARY

In an embodiment, a roller bearing seal includes a seal case, anelastomer lip, and a polymer shroud. The elastomer lip is attached tothe inner diameter edge of the seal case to complete a seal between theseal case and a wear ring while permitting rotation of the seal case andthe rubber lip about the wear ring. The polymer shroud wraps partiallyaround a non-bearing side of the seal case and shrouds the seal. Thepolymer shroud includes an inner diameter leg configured to attach thepolymer shroud to the wear ring with the inner diameter leg at anoblique angle to the wear ring.

In an embodiment, a polymer shroud for a roller bearing seal includes ashroud body and an inner diameter leg being respective portions of asingle continuous part. The shroud body encircles a rotation axis of thepolymer shroud and extends predominantly in directions orthogonal to therotation axis from an inner diameter to an outer diameter. The innerdiameter leg connects to the shroud body at the inner diameter,encircles the rotation axis, and is oriented at an oblique angle to therotation axis to extend both (a) radially inward from the inner diameterand (b) axially away from the inner diameter along a first directionparallel to the rotation axis.

In an embodiment, a method of assembling a roller bearing seal includespositioning a polymer shroud to wrap partially around a non-bearing sideof a seal case, and interference fitting an inner diameter leg of thepolymer shroud onto a wear ring encircled by the seal case, the innerdiameter leg being oriented at an oblique angle to its rotation axis toextend both (a) radially outward from the wear ring and (b) axially awayfrom inner diameter of the inner diameter leg along a first directionparallel to the rotation axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate a roller bearing seal in an exemplaryimplementation, according to an embodiment.

FIG. 3 provides a more detailed view of the roller bearing seal of FIGS.1 and 2 showing a temperature-robust polymer shroud.

FIG. 4 illustrates another roller bearing seal with a temperature-robustpolymer shroud, which is mounted on a wear ring, according to anembodiment.

FIGS. 5 and 6 illustrate the temperature-dependent behavior of asimplified polymer shroud implemented in a roller bearing seal mountedon a steel wear ring, according to an embodiment.

FIGS. 7, 8, and 9 show a roller bearing seal with a temperature-robustpolymer shroud mounted on a wear ring, and illustrate responsiveness ofthe temperature-robust polymer shroud to temperature changes, accordingto an embodiment.

FIGS. 10 and 11 illustrate a temperature-robust polymer shroud forimplementation in a roller bearing seal, according to an embodiment.

FIG. 12 illustrates a roller bearing seal implementing thetemperature-robust polymer shroud of FIGS. 10 and 11, according to anembodiment.

FIGS. 13, 14, and 15 illustrate shape change of one exemplarytemperature-robust polymer shroud in response to temperature changes, inan embodiment.

FIG. 16 illustrates a method for assembling a roller bearing seal havinga temperature-robust polymer shroud, according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 1 and 2 illustrate a roller bearing seal 110 in an exemplaryimplementation, wherein two instances of roller bearing seal 110 areused to seal a roller bearing 100. In the implementation depicted inFIGS. 1 and 2, roller bearing 100 is mounted on a journal 280 of anaxle, such as a rail car axle or a truck axle. FIG. 1 shows a rollerbearing 100 in perspective view with a cut-away section to reveal innerparts. For clarity of illustration, journal 280 is omitted in FIG. 1.FIG. 2 shows a full section view of roller bearing 100 mounted onjournal 280 with the section being taken along the rotation axis 190 ofjournal 280. FIGS. 1 and 2 are best viewed together in the followingdescription.

Roller bearing 100 includes two strings of tapered rollers 150: aninboard string of tapered rollers 150(1) near inboard end 102 of journal280, and an outboard string of tapered rollers 150(2) near outboard end104 of journal 280. Each tapered roller 150 has the shape of a truncatedcone. Tapered rollers 150(1) are tapered in the opposite direction oftapered rollers 150(2). Tapered rollers 150(1) and 150(2) are positionedbetween a bearing cup 130 and respective bearing cones 140(1) and140(2). Bearings cones 140 are mounted on journal 280.

Roller bearing seals 110(1) and 110(2) encircle the rotation axis ofjournal 280 and seal the inboard and outboard sides, respectively, ofroller bearing 100. Roller bearing seals are mounted on respective wearrings 120(1) and 120(2) affixed to and encircling journal 280. Wearrings 120 encircle rotation axis 190. Roller bearing 100, roller bearingseals 110, and wear rings 120 cooperate to form a roller bearingassembly that may be mounted on a journal, for example journal 280.

In the embodiment depicted in FIGS. 1 and 2, roller bearing 100 furtherincludes a spacer ring 132 between bearing cones 140(1) and 140(2) toensure accurate positioning of bearing cones 140(1) and 140(2). Withoutdeparting from the scope hereof, bearing cones 140(1) and 140(2) mayinstead be sized so as to be in direct contact with each other with noneed for spacer ring 132; or bearing cones 140(1) and 140(2) may beimplemented in a single, integrally formed two-sided bearing cone. Asjournal 280 rotates relative to bearing cup 130, tapered rollers 150(1)and 150(2) roll on inward facing raceways 234(1) and 234(2) of bearingcup 130.

In an embodiment, roller bearing 100 includes frames 160(1) and 160(2).Tapered rollers 150(1) and 150(2) are seated in seats of respectiveframes 160(1) and 160(2), and frames 160(1) and 160(2) serve to maintaina desired spacing between tapered rollers 150 of each string.

In the embodiment depicted in FIGS. 1 and 2, journal 280 forms a fillet282 at its inboard end 102 and terminates in a tapered guide portion 284at its outboard end 104. Tapered guide portion 284 eases installation ofroller bearing 100 onto journal 280. Roller bearing 100 is axiallyclamped between (a) a backing ring 172 backed up against fillet 282 and(b) a retaining cap 174 affixed to outboard end 104 of journal 280 viabolts (or screws) 176. More specifically, bearing cones 140 aresandwiched between wear rings 120, which in turn are clamped betweenbacking ring 172 and retaining cap 174.

Without departing from the scope hereof, roller bearing 100 may be adifferent type of roller bearing than shown in FIGS. 1 and 2, such as asingle-row tapered roller bearing, a quadruple-row tapered rollerbearing, a cylindrical roller bearing, a spherical roller bearing, or aball bearing. In such alternative embodiments, bearing cup 130, taperedrollers 150, and bearing cones 140 are replaced by suitable componentsto form the corresponding type of roller bearing; yet these embodimentsof roller bearing 100 still include roller bearing seals 110. Likewise,the tapering directions of tapered rollers 150 may be inverted as fromwhat is depicted in FIGS. 1, 2, and 3. Furthermore, while operation ofroller bearing 100 typically involves rotation of journal 280 relativeto a non-rotating bearing cup 130, the roles may be reversed such thatbearing cup 130 rotates about a stationary journal 280, or bearing cup130 and journal 280 rotate at different speeds.

FIG. 3 provides a more detailed view of roller bearing seal 110 in crosssection. In particular, FIG. 3 shows a temperature-robust polymer shroud310 of roller bearing seal 110. The section 100′ depicted in FIG. 3 isequivalent to the upper portion of the full section view of rollerbearing seal 110(2) shown in FIG. 2, but applies to roller bearing seal110(1) as well.

Roller bearing seal 110 includes temperature-robust polymer shroud 310,a seal case 320, an elastomer lip 322, an insert 324, and a rotor 330,each of which encircles rotation axis 190. Seal case 320 is coupled tobearing cup 130. Rotor 330 is mounted on wear ring 120.Temperature-robust polymer shroud 310 is interference fitted on wearring 120 and wraps partially around the non-bearing side 325 of sealcase 320. Non-bearing side 325 of seal case 320 is a side of seal case320 facing away from roller bearing 100. Elastomer lip 322 is affixed toan inner diameter edge 321 of seal case 320 and seals seal case 320 to aradially outward facing surface 350 of wear ring 120. Insert 324 ismounted in seal case 320 and forms a labyrinth seal with rotor 330.Herein, “inner diameter” of a part encircling rotation axis 190 refersto the perimeter of the part that is closest to rotation axis 190.Similarly, “outer diameter” of a part encircling rotation axis 190refers to the perimeter of the part that is farthest from rotation axis190

Temperature-robust polymer 310 is a single continuous part that iscomposed of a polymer, such as an engineering thermoplastic (such aspolyester or a composite material), an ultraviolet-resistant polymer, athermoset, or an ultraviolet-resistant engineering thermoplastic.Temperature-robust polymer 310 includes an inner diameter leg 312 and ashroud body 314, each encircling rotation axis 190. Shroud body 314extends predominantly in directions orthogonal to rotation axis 190 froman inner diameter 370 to an outer diameter 372. Inner diameter leg 312connects to shroud body 314 at inner diameter 370, and is oriented at anoblique angle to rotation axis 190 and radially outward facing surface350 to extend both (a) radially inward from inner diameter 370 and (b)axially away from inner diameter 370 along a direction 390 parallel torotation axis 190. In the embodiment shown in FIG. 3, temperature-robustpolymer shroud 310 further includes an outer diameter leg 316 thatconnects to outer diameter 372 of shroud body 314. Herein, “radiallyinward” refers to a direction toward rotation axis 190, “radiallyoutward” refers to a direction away from rotation axis 190, and an“axial” direction refers to a direction that is substantially parallelto rotation axis 190. Outer diameter leg 316 encircles rotation axis 190and extends predominantly along rotation axis 190 in a directionopposite direction 390. Without departing from the scope hereof,temperature-robust polymer shroud 310 may be provided without outerdiameter leg 316.

When journal 280 rotates relative to bearing cup 130, temperature-robustpolymer shroud 310 and rotor 330 rotate with journal 280, while sealcase 320 (together with elastomer lip 322 and insert 324) remains fixedto bearing cup 130, such that temperature-robust polymer shroud 310 androtor 330 rotate relative to seal case 320 (and elastomer lip 322 andinsert 324).

Roller bearing seal 110 provides three layers of sealing between rollerbearing 100 and the outside environment: the labyrinth seal betweeninsert 324 and rotor 330, the contact seal between elastomer lip 322 andwear ring 120, and a further protection (shrouding) of this contact sealprovided by temperature-robust polymer shroud 310. Temperature-robustpolymer shroud 310 may further serve to block or attenuate infraredradiation generated in the contact seal between elastomer lip 322 andwear ring 120 as the contact seal between elastomer lip 322 and wearring 120 heats up during operation. Such infrared radiation is oftenused as the basis for detecting, for example by wayside infraredsensors, overheated roller bearings and taking such overheated rollerbearings out of use.

Wear ring 120 is typically made of steel, or another material having alower thermal expansion coefficient than the polymer oftemperature-robust polymer shroud 310. Hence, wear ring 120 andtemperature-robust polymer shroud 310 do not expand and contract in thesame manner when subjected to temperature changes. As discussed infurther detail below in reference to FIGS. 7, 8, and 9,temperature-robust polymer shroud 310 is, by virtue of the interferencefitted inner diameter leg 312 and its oblique angle to radially outwardfacing surface 350, capable of maintaining contact with wear ring 120across a wide temperature range even when the thermal expansioncoefficient of wear ring 120 is lower than that of temperature-robustpolymer shroud 310. Temperature-robust polymer shroud 310 is thereforecapable of protecting (shrouding) the contact seal associated withelastomer lip 322 over a wide temperature range. In addition, due to themaintained contact over the wide temperature range, temperature-robustpolymer shroud 310 prevents infrared light from escaping roller bearing100 through gaps in the seal between wear ring 120 andtemperature-robust polymer shroud 310. In the absence of thistemperature-robustness, such infrared light could result in anerroneously high temperature reading by a wayside infrared sensor andforce removal of the roller bearing from use. In one embodiment,temperature-robust polymer shroud 310 is capable of maintaining contactwith radially outward facing surface 350 along a path that fullyencircles rotation axis 190 in a temperature range spanning from −40degrees Fahrenheit to 176 degrees Fahrenheit. These temperatures arereasonable limits for the operating range of a roller bearing, such asroller bearing 100, implemented in a rail car or a truck, for example.

In an embodiment, rotor 330 is composed of, or includes,fiber-reinforced polymer. In this embodiment, the difference in thermalexpansion coefficient between rotor 330 and wear ring 120 is less thanthe difference in thermal expansion coefficient betweentemperature-robust polymer shroud 310 and wear ring 120. Hence, rotor330 may remain properly seated on wear ring 120 over at least thetemperature range associated with adequate coupling betweentemperature-robust polymer shroud 310 and wear ring 120.

Although FIG. 3 shows wear ring 120 being coupled to journal 280 via aring 340, wear ring 120 may be mounted directly on journal 280 withoutdeparting from the scope hereof. Furthermore, it is understood that theapparent overlap conflict between wear ring 120 and each of innerdiameter leg 312, elastomer lip 322 and rotor 330 is a machine-drawingartifact. The drawing shows the individual parts as they are to bemanufactured but, in assembly, one or more of the parts flexes or iscompressed to provide a tight fit.

In one embodiment, temperature-robust polymer shroud 310 forms a rib 318protruding toward seal case 320 and encircling rotation axis 190.Although shown in FIG. 3 as touching seal case 320, rib 318 may be at adistance from seal case 320, without departing from the scope hereof.Without departing from the scope hereof, rib 318 may be implemented as aseries of ribs each spaced apart from its neighboring ribs, wherein theseries of ribs encircles rotation axis 190.

FIG. 4 illustrates, in cross section, another roller bearing seal 400with temperature-robust polymer shroud 310. FIG. 4 shows roller bearingseal 400 as mounted on wear ring 120(2). Temperature-robust rollerbearing seal 400 may replace roller bearing seal 110 in the sealing ofroller bearing 100 discussed above in reference to FIGS. 1, 2, and 3.

Roller bearing seal 400 includes temperature-robust polymer shroud 310,a seal case 420, and an elastomer lip 422. Seal case 420 is similar toseal case 320, but is not coupled with an insert 324. Elastomer lip 422is similar to elastomer lip 322 except that elastomer lip 422, in theabsence of insert 324 and rotor 330, may be larger than elastomer lip322 to provide an increased area of contact, or two separate areas ofcontact, between elastomer lip 422 and wear ring 120. This increasedcontact may improve the sealing provided by the contact seal betweenelastomer lip 422 and wear ring 120, as compared to the sealing providedby the contact seal between elastomer lip 322 and wear ring 120 inroller bearing seal 110.

FIGS. 5 and 6 illustrate the temperature-dependent behavior of asimplified polymer shroud 510 implemented in a roller bearing seal 500mounted on a steel wear ring 530. FIG. 5 shows the configuration ofroller bearing seal 500 at a design temperature such as the temperaturemost commonly encountered during use of roller bearing seal 500, andFIG. 6 shows the configuration of roller bearing seal 500 at atemperature greater than the design temperature. FIGS. 5 and 6 are bestviewed together in the following description.

Roller bearing seal 500 includes polymer shroud 510, a seal case 520,and an elastomer lip 522. Elastomer lip 522 seals seal case 520 to steelwear ring 530. Steel wear ring 530 may be similar to wear ring 120, sealcase 520 may be similar to seal case 320 or seal case 420, and elastomerlip 522 may be similar to elastomer lip 322 or elastomer lip 422.Polymer shroud 510 includes a shroud body 512 and an outer diameter leg514. Polymer shroud 510 wraps partially around anon-bearing side 525 ofseal case 520. A radially inward facing surface 518 of shroud body 512is mounted directly to a radially outward facing surface 550 of steelwear ring 530. The angle between shroud body 512 and steel wear ring 530is approximately ninety degrees.

When the temperature is increased above the design temperature, polymershroud 510 expands radially outward along a direction 690 away fromrotation axis 190 (not shown in FIGS. 5 and 6). Since the rate ofexpansion of polymer shroud 510 is greater than the rate of expansion ofsteel wear ring 530, radially inward facing surface 518 of polymershroud 510 loses contact with radially outward facing surface 550 ofsteel wear ring 530, allowing ingress of water and contaminants to thecontact seal formed by elastomer lip 522. This increases the rate ofwear of the interface between elastomer lip 522 and wear ring 530,potentially resulting in failure of roller bearing seal 500.

At temperatures significantly below the design temperature, theassociated thermal contraction of polymer shroud 510 may cause polymershroud 510 to break from the increased forces at the interface betweenradially inward facing surface 180 and radially outward facing surface550 of the lesser-contracting steel wear ring 530.

FIGS. 7, 8, and 9 illustrate a roller bearing seal 700 having atemperature-robust polymer shroud 710 mounted on a wear ring 730, andthe response of temperature-robust polymer shroud 710 to temperaturechanges. FIGS. 7, 8, and 9 show roller bearing seal 700 in a crosssection similar to that used in FIGS. 3 and 4. Roller bearing seals 110and 400 are embodiments of roller bearing seal 700. A pair of rollerbearing seals 700 may replace roller bearing seals 110 in the sealing ofroller bearing 100. Generally, roller bearing seal 700 is configured formounting on a wear ring, such as wear ring 730, to seal a roller bearingseal. FIGS. 7, 8, and 9 show the configuration of temperature-robustpolymer shroud 710 at a central temperature, a temperature greater thanthe central temperature, and a temperature lower than the centraltemperature, respectively. FIGS. 7, 8, and 9 are best viewed together inthe following description. The central temperature is, for example, roomtemperature or a temperature under which roller bearing seal 700 isassembled. Alternatively, the central temperature may be a temperaturethat is centered between the upper and lower temperature limits forproper operation of a roller bearing seal implementingtemperature-robust roller bearing seal 700. The temperature associatedwith FIG. 8 is, for example, an operational temperature of rollerbearing seal 700. The temperature associated with FIG. 9 is, forexample, a temperature encountered when roller bearing seal 700 sitsidle in a cold environment.

Roller bearing seal 700 includes temperature-robust polymer shroud 710,a seal case 720, and an elastomer lip 722 affixed to the inner diameteredge of seal case 720. Roller bearing seal 700 is configured to bemounted on a wear ring 730, for example on wear ring 120, in a mannersimilar to that discussed above for roller bearing seals 110 and 400.Elastomer lip 722 forms a contact seal between seal case 720 and aradially outward facing surface 750 of wear ring 730. Temperature-robustpolymer shroud 710 is interference fitted onto radially outward facingsurface 750 and wraps partially around a non-bearing side 725 of sealcase 720 to protect (shroud) the contact seal formed by elastomer lip722. In operation, temperature-robust polymer shroud 710 is stationaryrelative to wear ring 730, whereas seal case 720 together with elastomerlip 722 are free to rotate relative to wear ring 730.

Temperature-robust polymer shroud 710 is a single continuous part thatis composed of a polymer, such as an engineering thermoplastic (such aspolyester or a composite material), an ultraviolet-resistant polymer, athermoset, or an ultraviolet-resistant engineering thermoplastic.Temperature-robust polymer shroud 710 includes an inner diameter leg 712and a shroud body 714, each encircling rotation axis 190. Shroud body714 extends predominantly in directions orthogonal to rotation axis 190from an inner diameter 770 to an outer diameter 772. Inner diameter leg712 connects to shroud body 714 at inner diameter 770, and is orientedat an oblique angle to rotation axis 190 and radially outward facingsurface 750 to extend both (a) radially inward from inner diameter 770and (b) axially away from inner diameter 770 along a direction 790parallel to rotation axis 190. In the embodiment shown in FIGS. 7, 8,and 9, temperature-robust polymer shroud 710 further includes an outerdiameter leg 716 that connects to outer diameter 772 of shroud body 714.Outer diameter leg 716 encircles rotation axis 190 and extendspredominantly along rotation axis 190 in a direction opposite direction790. Without departing from the scope hereof, temperature-robust polymershroud 710 may be provided without outer diameter leg 716. Furthermore,seal case 720 may have shape differently from that shown in FIGS. 7, 8,and 9, without departing from the scope hereof. For example, seal case720 may terminate near the second ninety-degree bend away from elastomerlip 722.

Wear ring 730 is composed of a material characterized by a lower thermalexpansion coefficient than that of temperature-robust polymer shroud710. In one embodiment, wear ring 730 is composed of steel.

At the central temperature (see FIG. 7), the radially innermost surface718 of inner diameter leg 712 contacts radially outward facing surface750, with the contact interface encircling rotation axis 190. Innerdiameter leg 712 forms an angle 740 with radially outward facing surface750 and rotation axis 190. Angle 740 is, for example, in the range from20 to 50 degrees.

As shown in FIG. 8, when the temperature increases above the centraltemperature while wear ring 730 restricts temperature-robust polymershroud 710 from radially inward expansion, the associated thermalexpansion of temperature-robust polymer shroud 710 causestemperature-robust polymer shroud 710 to change shape and “roll” awayfrom seal case 720, thereby increasing the angle between inner diameterleg 712 and wear ring to an angle 840 that is greater than angle 740.However, in contrast with the behavior of simplified polymer shroud 510lacking an obliquely angled inner diameter leg interference fitted ontoa wear ring, temperature-robust polymer shroud 710 does not lose contactwith wear ring 730 when the temperature increases (at least up to acertain temperature). In one embodiment, temperature-robust polymershroud 710 is configured to maintain contact with wear ring 730, along apath that encircles rotation axis 190, up to the upper extreme of atemperature range required by an industry standard specifying operatingparameters for a roller bearing in a particular use setting, such as anindustry standard for rail cars. More specifically, outer diameter 772of shroud body 714 shifts in direction 790 and moves radially outward,as indicated by arrow 810. Concurrently, portions of inner diameter leg712 away from contact with wear ring 730 also shift in direction 790 andmove radially outward, as indicated by arrow 812. However, at least aportion of the radially innermost surface 718 of temperature-robustpolymer shroud 710 remains in contact with radially outward facingsurface 750 of wear ring 730. Hence, temperature-robust polymer shroud710 is capable of protecting the contact seal formed by elastomer lip722 at temperatures significantly above the central temperature.

As shown in FIG. 9, when the temperature decreases below the centraltemperature while wear ring 730 restricts temperature-robust polymershroud 710 from radially inward expansion, the associated thermalcontraction of temperature-robust polymer shroud 710 causestemperature-robust polymer shroud 710 to change shape, in a manneropposite that associated with a temperature increase, and “roll” towardseal case 720, thereby decreasing the angle between inner diameter leg712 and wear ring to an angle 940 that is smaller than angle 740. Thechange of shape accommodates the forces from the lesser-contracting wearring 730 and prevents the breakage of temperature-robust polymer shroud710, which is characteristic of simplified polymer shroud 510. Hence,temperature-robust polymer shroud 710 is capable of protecting thecontact seal formed by elastomer lip 722 at temperatures significantlybelow the central temperature. In one embodiment, temperature-robustpolymer shroud 710 is configured to remain intact and maintain contactwith wear ring 730, along a path that encircles rotation axis 190, downto the lower extreme of a temperature range required by an industrystandard specifying operating parameters for a roller bearing in aparticular use setting, such as an industry standard for rail cars.Furthermore, with the issue of cold-temperature induced breakage of thepolymer shroud resolved by the shape change facilitated by the obliquelyangle inner diameter leg 712, it is possible to form a tighterinterference fit between temperature-robust polymer shroud 710 and wearring 730. More specifically, outer diameter 772 of shroud body 714shifts in a direction opposite direction 790 and also moves radiallyinward, as indicated by arrow 910. Concurrently, portions of innerdiameter leg 712 away from contact with wear ring 730 also shift in adirection opposite direction 790 and move radially inward, as indicatedby arrow 912. The radially innermost surface 718 of temperature-robustpolymer shroud 710 (which may be a slightly different portion oftemperature-robust polymer shroud 710 than at the temperaturesassociated with FIGS. 7 and 8) remains in contact with radially outwardfacing surface 750 of wear ring 730.

In one embodiment, temperature-robust polymer shroud 710 is capable ofremaining both intact and in contact with wear ring 730 at all pointsalong a path that encircles rotation axis 190 at least for alltemperatures in the range from −40 degrees Fahrenheit to 176 degreesFahrenheit. In another embodiment, temperature-robust polymer shroud 710is capable of remaining both intact and in contact with wear ring 730 atall points along a path that encircles rotation axis 190 at least forall temperatures in the range from approximately −20 degrees Fahrenheitto 150 degrees Fahrenheit.

Although FIGS. 7, 8, and 9 show the contact between radially innermostsurface 718 of inner diameter leg 712 and radially outward facingsurface 750 of wear ring 730 as having only a point-type extent alongrotation axis 190, it is understood that the actual contact interface islikely to be extended along some portion of rotation axis 190.

FIGS. 10 and 11 illustrate one temperature-robust polymer shroud 1000for implementation in a roller bearing seal. Polymer shroud 1000 is anembodiment of temperature-robust polymer shroud 710. FIG. 10 showstemperature-robust polymer shroud 1000 as viewed along rotation axis190, and FIG. 11 is a view of section A-A′ indicated in FIG. 10. FIGS.10 and 11 are best viewed together in the following description.

Temperature-robust polymer shroud 1000 includes a shroud body 1014, aninner diameter leg 1012, and an outer diameter leg 1016. Inner diameterleg 1012 is at an angle 1040 to rotation axis 190. Shroud body 1014 mayform a rib 1020, such as rib 318, protruding in the same generaldirection as outer diameter leg 1016. Without departing from the scopehereof, rib 1020 may be implemented as a series of ribs each spacedapart from its neighboring ribs, wherein the series of ribs encirclesrotation axis 190. At approximately room temperature and before mountingtemperature-robust polymer shroud 1000 to a wear ring, angle 1040 may bein the range between 20 and 50 degrees, for example around 35 degrees,and shroud body 1014 is non-orthogonal to rotation axis 190. In oneembodiment (a) the inner diameter 1080 of temperature-robust polymershroud 1000 is in the range from 8 inches to 24 inches, for examplearound 14 inches, (b) the outer diameter 1082 of temperature-robustpolymer shroud 1000 is in the range from 5 inches to 30 inches, forexample around 9 inches, and (c) the thickness 1050 oftemperature-robust polymer shroud 1000 is in the range from 0.02 inchesto 0.1 inches, for example around 0.05 inches.

FIG. 12 shows a section of one roller bearing seal 1200 implementingtemperature-robust polymer shroud 1000, in pictorial view. Rollerbearing seal 1200 is similar to roller bearing seal 110. Roller bearingseal 1200 includes temperature-robust polymer shroud 1000, a seal case1220, an elastomer lip 1222 affixed to the inner diameter of seal case1220, an insert 1224 mounted in seal case 1220, and a rotor 1230. Sealcase 1220, elastomer lip 1222, insert 1224, and rotor 1230 are similarto seal case 320, elastomer lip 322, insert 324, and rotor 330,respectively.

In an alternative embodiment, not shown in FIG. 12, bearing seal 1200 isprovided without insert 1224 and without rotor 1230. In this embodiment,roller bearing seal 1200 is similar to roller bearing seal 400. Inanother alternative embodiment, also not shown in FIG. 12, insert 1224is omitted and rotor 1230 is instead matched to a feature of seal case1220 protruding in the direction toward the bearing to be sealed byroller bearing seal 1200.

FIGS. 13, 14, and 15 are finite-element-analysis based stress plotssimulating the shape and maximum principal stress of an example oftemperature-robust polymer shroud 1000 when mounted on a wear ring 1310(such as wear ring 120 or 730) between seal case 1220 and a retainingcap 1320 (similar to retaining cap 174). FIGS. 13, 14, and 15 show theshape of temperature-robust polymer shroud 1000 at 75 degreesFahrenheit, 176 degrees Fahrenheit, and −40 degrees Fahrenheit,respectively. The plots of FIGS. 13, 14, and 15 show thattemperature-robust polymer shroud 1000 responds to temperature asdiscussed for temperature-robust polymer shroud 710 above in referenceto FIGS. 7, 8, and 9.

FIG. 16 illustrates one method 1600 for assembling a roller bearing sealhaving a temperature-robust polymer shroud. Method 1600 may be used toassemble roller bearing seal 310, 400, 700, and 1200.

Method 1600 includes step 1640 and 1650, which may be performedconcurrently. Step 1640 positions a temperature-robust polymer shroud towrap partially around a non-bearing side of a seal case. In one exampleof step 1640, temperature-robust polymer shroud 710 is positioned towrap partially around a non-bearing side 725 of seal case 720 mounted onwear ring 730. Step 1650 interference fits an inner diameter leg of thetemperature-robust polymer shroud onto a wear ring encircled by the sealcase. The inner diameter leg is oriented at an oblique angle to therotation axis of the temperature-robust polymer shroud to extend both(a) radially outward from the wear ring and (b) axially away from theinner diameter of the inner diameter leg along a first directionparallel to the rotation axis. In one example, inner diameter leg 712 oftemperature-robust polymer shroud 710 is interference fitted onto wearring 730, such that radially innermost surface 718 of inner diameter leg712 contacts radially outward facing surface 750 of wear ring 730.

Step 1650 may include a step 1652 of ensuring contact between the innerdiameter leg and the wear ring, along a path encircling the rotationaxis of the roller bearing seal, over a finite temperature range byvirtue of the oblique angle of the inner diameter leg relative to therotation axis. In one example, the oblique angle of inner diameter leg712 of temperature-robust polymer shroud 710 ensures temperature-robustcontact as discussed above in reference to FIGS. 7, 8, and 9.

In an embodiment, method 1600 further includes steps 1620 and 1630preceding step 1650. Step 1620 couples a rotor to the bearing-side of aseal case in a manner that allows for rotation of the rotor relative tothe seal case. In one example of step 1620, a rotor, such as rotor 1230,is coupled to a feature on the bearing-side of seal case 1220, asdiscussed above, while allowing for rotation of rotor 1230 relative toseal case 1220. Step 1620 may include steps 1622 and 1624. Step 1622inserts an insert into the bearing-side of the seal case, and step 1624couples the rotor to the insert in a manner that allows for rotation ofrotor relative to the insert. In one example of steps 1622 and 1624,insert 1224 is inserted in the bearing-side of seal case 1220, and rotor1230 is coupled to insert 1224, while allowing for rotation of rotor1230 relative to insert 1224.

Optionally, method 1600 includes a step 1610 preceding step 1640. Step1610 injection molds the temperature-robust polymer shroud. In oneexample of step 1610, temperature-robust polymer shroud 710 or 1000 isinjection molded.

Changes may be made in the above systems and methods without departingfrom the scope hereof. It should thus be noted that the matter containedin the above description and shown in the accompanying drawings shouldbe interpreted as illustrative and not in a limiting sense. Thefollowing claims are intended to cover generic and specific featuresdescribed herein, as well as all statements of the scope of the presentsystems and methods, which, as a matter of language, might be said tofall therebetween.

What is claimed is:
 1. A roller bearing seal, comprising: a seal case;an elastomer lip, attached to an inner diameter edge of the seal case,to complete a seal between the seal case and a wear ring whilepermitting rotation of the seal case and the elastomer lip about thewear ring; and a polymer shroud wrapping partially around a non-bearingside of the seal case and shrouding the seal, the polymer shroudincluding an inner diameter leg encircling a rotation axis of the rollerbearing seal, the inner diameter leg being configured to attach thepolymer shroud to the wear ring with the inner diameter leg being at anoblique angle to the wear ring along entire circumference of the wearring.
 2. The roller bearing seal of claim 1, the polymer shroudincluding a shroud body integrally connected to the inner diameter legand extending radially outward from the inner diameter leg and along theseal case, the polymer shroud forming a bend between the inner diameterleg and the shroud body such that the inner diameter leg is bent awayfrom the elastomer lip.
 3. The roller bearing seal of claim 2, thepolymer shroud being configured to, when mounted on the wear ring,change shape in response to temperature changes such that deviation fromplanarity of the shroud body increases with temperature.
 4. The rollerbearing seal of claim 1, the oblique angle being configured to ensurecontact between the polymer shroud and the wear ring over a finitetemperature range, the contact encircling the rotation axis.
 5. Theroller bearing seal of claim 4, the polymer shroud being configured tomaintain the contact over a temperature range spanning at least from −40degrees Fahrenheit to 176 degrees Fahrenheit.
 6. The roller bearing sealof claim 1, when mounted to the wear ring the polymer shroud beingconfigured to flex (a) radially outward and away from the seal case withincreasing temperature and (b) radially inward and toward the seal casewith decreasing temperature, while maintaining the contact.
 7. Theroller bearing seal of claim 1, further comprising: an insert mounted onbearing-side of the seal case; and a rotor configured to attach to thewear ring and form a labyrinth seal with the insert.
 8. Theroller-bearing seal of claim 1, the polymer shroud being configured toat least attenuate infrared radiation generated in a roller bearingsealed by the roller-bearing seal during operation of the rollerbearing.
 9. A roller bearing assembly, comprising: a wear ring; a rollerbearing seal including: a seal case, an elastomer lip, attached to innerdiameter edge of the seal case, to complete a seal between the seal caseand a wear ring while permitting rotation of the seal case and theelastomer lip about the wear ring, and a polymer shroud wrappingpartially around a non-bearing side of the seal case and shrouding theseal, the polymer shroud including an inner diameter leg encircling arotation axis of the roller bearing seal, the inner diameter leg beingconfigured to attach the polymer shroud to the wear ring with the innerdiameter leg being at an oblique angle to the wear ring along entirecircumference of the wear ring, the polymer shroud having higher thermalexpansion coefficient than the wear ring; and a roller bearing sealed bythe roller bearing seal.
 10. The roller bearing assembly of claim 9, thewear ring being composed of steel.
 11. The roller bearing assembly ofclaim 9, the polymer shroud further including a shroud body encirclingthe rotation axis of the polymer shroud and extending predominantly indirections orthogonal to the rotation axis from an inner diameter of theshroud body to an outer diameter of the shroud body, wherein, along theentire circumference of the wear ring, the inner diameter leg extendsboth (a) radially inward from the inner diameter of the shroud body and(b) axially away from the inner diameter of the shroud body along afirst direction parallel to the rotation axis and away from the sealcase.
 12. The roller bearing assembly of claim 11, the polymer shroudfurther including an outer diameter leg that connects to the shroud bodyat the outer diameter of the shroud body, encircles the rotation axis,and extends predominantly along the rotation axis in a directionopposite the first direction.
 13. A polymer shroud for a roller bearingseal, comprising: a shroud body encircling a rotation axis of thepolymer shroud and extending predominantly in directions orthogonal tothe rotation axis from an inner diameter of the shroud body to an outerdiameter of the shroud body; and an inner diameter leg that connects tothe shroud body at the inner diameter of the shroud body and encirclesthe rotation axis, wherein, along the entire inner diameter of theshroud body, the inner diameter leg is oriented at an oblique angle tothe rotation axis to extend both (a) radially inward from the innerdiameter of the shroud body and (b) axially away from the inner diameterof the shroud body along a first direction parallel to the rotationaxis; the shroud body and the inner diameter leg being respectiveportions of a single continuous part.
 14. The polymer shroud of claim13, further comprising an outer diameter leg that connects to the shroudbody at the outer diameter of the shroud body, encircles the rotationaxis, and extends predominantly along the rotation axis in a directionopposite the first direction.
 15. The polymer shroud of claim 13,thermal expansion coefficient of the polymer shroud exceeding thermalexpansion coefficient of steel.
 16. The polymer shroud of claim 13, theshroud body being configured to change shape, wherein the outer diameterof the shroud body shifts in the first direction and moves radiallyoutward when subjected to increasing temperature and when restrictedfrom radially inward expansion.
 17. The polymer shroud of claim 16,configured such that the outer diameter of the shroud body shiftsopposite the first direction and moves radially inward when subjected todecreasing temperature decrease and when restricted from radially inwardexpansion.